The present invention relates to a device for opening shell fishes of the type having two shell halves normally held closed against each other by a muschle, such as oysters, clams and the like.
Oyster shell openers hitherto known usually comprise a knife or wedge element adapted to be inserted at the edge defined between the two shell halves at one end of the oyster shell and an abutment for holding the shell at the other end thereof against the outward force exerted by wedge element during the opening operation. In one type of oyster opening tool which has been proposed, for instance, in Canadian Pat. Nos. 131,370 and 149,909, the wedge element is connected to a vertically swingable lever which is actuated by hand so as to force the wedge element to horizontally penetrate between the shell halves upon downward movement of the lever, thereby opening the oyster shell. Such implement, however, is generally bulky in construction and must be mounted for firm support such as by being clamped to a table or the like, and thus cannot be conveniently carried as such, for instance, in one's pocket.
A more readily transportable type of oyster opener which has been proposed in Canadian Patent No. 896,819 takes the form of a pair of pliers having one jaw member provided with the wedge element and the other jaw member with the abutment for the oyster shell. This type of oyster opener presents the disadvantage that only different oysters varying over a relatively narrow range of sizes and shapes can be effeciently opened since oysters of large sizes will require an impractical wide spacing of the handles of the pliers, thus resulting in great difficulty to close the jaw members to open the shell. Also, the manner in which the oyster is held between the jaw members does not provide a stable support while opposed forced are applied at localised points on the shell; as a result, the oyster can easily slip out of the jaw members.
In addition, most known oyster shell openers do not permit the shell to be completely opened in a single operation since it is often necessary after the shell halves have been separated apart to introduce through the small opening formed a knife so as to cut the oyster muscle.